1. Field of the Invention
This invention relates to circuitry for a color display device and more particularly to circuitry for modifying the luminescence of one color with respect to other colors on a multicolor display device.
2. Description of the Prior Art
In electronic flight instrument systems (EFIS) certain mechanical instruments have been replaced electronically by displaying the image of the mechanical instrument on a display device. One example of a mechanical instrument that has been replaced by an image on a display device is an attitude direction indicator (ADI) which shows the attitude of an aircraft by displaying various symbols, lettering, lines and background in various colors. Another example of a mechanical instrument which has been replaced by displaying an image on a display device is a horizontal situation indicator (HSI) which also displays a number of symbols, a compass rose, lettering, lines and boxes enclosing lettering in various colors. For example, in the horizontal situation indicator display the following colors are observed, red, magenta, white, green, yellow, and orange. Colors that may be seen in the attitude direction indicator are red, green, orange, yellow and white. In addition, a dark blue background is shown in the upper half of the display and a brown background is shown in the lower half of the display. During flight of an aircraft, ambient lighting, impinging light, etc. may make it extremely difficult to clearly observe the display including certain flags, for example, the lettering "auto test failed". Flags may be placed on the display over symbols in various colors formed during the stroke mode of the display device or over a background formed during the raster mode of the display device. In the stroke mode, the display device paints out a symbol directly. In the raster mode, the display device paints in a raster pattern, such as from left to right, across the display device with each new sweep indexed vertically.
It is therefore desirable to increase the luminescence of the colors used to provide warning flags on the display device.
It is further desirable to provide an increase in the luminescence of the color red during the formation of certain warning flags on the display device.
It is further desirable to increase the luminescence of certain colors on the display device relative to other colors to provide sufficient luminescence for observation by the naked eye.